The present invention relates to a method and to apparatus for detecting electromagnetic protection defects in electrical conductors, in particular those referred to as “harnesses”, namely bundles of electrical conductors that are hardened, i.e. shielded against electromagnetic disturbances, and that are used for electrically interconnecting various devices in a complex electrical installation that needs to function properly, even in the event of electromagnetic disturbances. Naturally, each electrical conductor, constituted by at least one electrically conductive.wire contained in a tube constituting an electrical insulator, may additionally include individual shielding giving it an additional level of protection against electromagnetic disturbances. By way of example, such harnesses are used on board aircraft, ships, tanks, etc. . . . .